Engine-clutch control interlock system

Abstract

Possible damage to a clutch caused by engagement or disengagement when the engine is running at a high speed is prevented by an engine-clutch control interlock system which prevents the clutch from being engaged or disengaged except when the engine is running at a speed below a nominal, selected idle speed. The system comprises an engine speed monitor which produces a speed signal indicative of whether the engine is running above or below the selected idle speed, a clutch control monitor which produces a signal indicative of whether or not a clutch actuator control signal is being generated and a clutch status monitor which produces a signal indicative of whether the clutch is engaged or disengaged. A clutch actuator signal is conducted to the clutch either to engage or disengage it only when the monitors indicate that a clutch control signal is being generated and the engine is running below the nominal idle speed. A speed control signal is conducted to the engine speed controller only when the clutch status monitor indicates that a disengaged clutch has engaged.

I claim: 
     
       1. In a power train that includes an engine having an engine speed control means for controlling the speed of the engine in response to an engine speed control signal generated and selectively conducted to the speed controller and a clutch having a clutch control means for engaging and disengaging the clutch in response to a clutch actuator signal, an engine and clutch control interlock system comprising means for monitoring engine speed and producing a speed signal indicative of whether the engine is running at a speed above or below a selected nominal idle speed; means for generating and monitoring a clutch control signal and producing a clutch control status signal indicative of whether or not a clutch control signal is being generated; means for monitoring the operating status of the clutch and producing a clutch status signal indicative of whether the clutch is engaged or disengaged; means responsive to the clutch control status signal and the speed signal for conducting the clutch actuator signal to the clutch control means of a disengaged clutch only when a clutch control signal is generated and the engine is running below the nominal idle speed; and means responsive to the clutch status signal for permitting a speed control signal to be conducted to the speed control means only after the clutch is engaged. 
     
     
       2. An engine and clutch control interlock system according to claim 1 and further comprising means responsive to the speed signal for continuing the conduction of a clutch actuator signal to the clutch control means as long as the engine is running at a speed above the nominal idle speed, even though the clutch control signal is terminated, and for terminating conduction of a clutch actuator signal to the clutch control means when the engine speed falls below nominal idle speed, provided no clutch control signal is being generated when the engine speed so falls. 
     
     
       3. An engine and clutch control interlock system according to claim 2 and further comprising means for maintaining conduction of a clutch actuator signal to the clutch control means, even though the clutch control signal is terminated and then restored, as long as the engine speed does not fall below nominal idle while the clutch control signal is terminated.